In a Long Term Evolution (LTE) system, a minimum time unit for scheduling by an evolved base station (eNB) is a subframe, each subframe includes 2 timeslots, and each timeslot further includes 7 symbols. For a user equipment (UE) scheduled in a subframe, the subframe includes a physical downlink control channel (PDCCH) of the UE. The PDCCH is used to carry scheduling information of the scheduled UE, and the scheduling information includes information such as a physical channel resource allocated for the UE and a specifically used modulation and coding scheme (MCS).
In a current LTE system, a PDCCH and a physical downlink shared channel (PDSCH) exist in a subframe in a time division manner, where the PDCCH is carried in first n symbols of the subframe, and n may be one of 1, 2, 3, and 4; and mapping of downlink data scheduled over the PDSCH starts from an (n+1)th symbol of the subframe. In a frequency domain, the PDCCH and the PDSCH are scattered, after interleaving processing, on bandwidths of the whole system to obtain frequency diversity gains. After performing demodulation and decoding on the PDCCH according to a payload size and an aggregation level of the PDCCH based on a cell-specific reference signal (CRS) and in a search space of the PDCCH, a UE uses a UE-specific radio network temporary identity (RNTI) or identity to descramble cyclical redundancy check (CRC) to check and determine the PDCCH of the UE, and performs corresponding receiving or sending processing, according to scheduling information in the PDCCH, on data scheduled over the PDCCH.
In an LTE system of a current or a subsequent version, introduction of technologies, such as multi-user multiple input multiple output (MIMO) and coordinated multiple points (CoMP), causes a limit on a capacity of a control channel; therefore, a PDCCH based on transmission in an MIMO precoding manner, namely, an enhanced physical downlink control channel (E-PDCCH) is introduced. The UE may demodulate the E-PDCCH based on a UE-specific reference signal (UERS).
The UERS demodulation manner is introduced in the transmission of the E-PDCCH; therefore, a suitable solution is required for implementing receiving and sending of the control channel.